0006541: Disabled TabSheets in JvPageControl are accessible through the keyboard

Description:

A disabled TabSheet in a JvPageControl is not accessible using the mouse, but it remains accessible through the keyboard using the left or right arrow when the focus is on the tab of the sheet.
I propose the following improvement: to deny access via the keyboard, or better, still in Delphi’s PageControl a disabled TabSheet is still accessible (even with mouse), to add a property to let the user choose the behavior it wants.
Thank you for your time

Could you check if the issue is still present in the latest GIT content? If yes, please provide the zipped sources of an application showing this.

(0021602)

CDametto

2019-01-25 11:27

The issue is still present in jvcl 3.50 with Delphi 10.3 rio

(0021740)

mh

2019-04-25 21:51

Interestingly, the VCL itself with a normal TPageControl does not respect the Enabled property of any TTabSheet at all.

So question: I can reproduce your issue on 10.3 Rio Update 1 with your simple demo fine enough, but is this really as it should work or asked otherwise: is the VCL wrong by not respecting Enabled of any TTabSheet?

(0021756)

mh

2019-04-27 13:36

Ok, WMLButtonDown contains this code:

if (RealIndex < PageCount) and (RealIndex >= 0) and
((hi.flags and TCHT_ONITEM) <> 0) then
if not Pages[RealIndex].Enabled then
begin
Msg.Result := 0;
Exit;
end;

which makes clicking on a disabled tab a no-op.
Keyboard handling most likely uses TPageControl.FindNextPage, which does not check for enabled or not. But that one is public and not virtual, so we cannot simply override it. Now what to do, besides wishing EMBT to respect enabled property?